Eight Common Problems in Die-Cutting Adhesive Labels and Their Solutions

In the production of self‑adhesive labels, die-cutting is an extremely important step; the quality of die-cutting directly affects the final product quality. Self‑adhesive labels are primarily composed of a three‑layer structure: face stock, adhesive layer, and release liner (which is coated with a silicone oil layer). During die-cutting, the blade must cut completely through the adhesive layer without damaging the silicone oil layer—this type of die-cutting technique is known as “precision die-cutting.” However, in actual production, due to the influence of numerous factors, it is often difficult to achieve this ideal condition, leading to various die‑cutting quality issues. In short, precision die-cutting is both the goal we strive for and the key tool that guides us in effectively resolving die‑cutting quality problems.

Bangbao Enterprise cites: Shenzhen Huxin Heng Technology has identified several common issues that frequently arise during die-cutting processes in its daily production. We’d like to share these insights with you all, hoping that after reading this article, our industry peers can avoid some unnecessary detours.

1. Cut Through the Base Paper

In cases of minor and non‑severe damage, the issue can be resolved by adjusting the pressure or increasing the die‑cutting speed. For large‑area or severe damage, the roller must be reworked. Generally speaking, the following are the main causes of die‑cutting damage to the backing paper:

1. Excessive die-cutting pressure

Excessive die-cutting pressure can easily lead to damage to the backing paper layer—but this simple principle is often overlooked by operators in daily production. While the die‑cutting process may seem straightforward, achieving high-quality results is far from easy. Properly adjusting die‑cutting pressure is a fundamental skill; the challenge lies in the fact that die‑cutting pressure is never entirely constant during operation. As far as I know, the stability of die‑cutting pressure is largely dependent on the quality of the die‑cutting equipment: well‑made die‑cutting machines maintain relatively stable pressure, whereas lower‑quality machines tend to exhibit poorer pressure stability. Therefore, operators must thoroughly understand the characteristics of the die‑cutting equipment they are using and promptly monitor and adjust the machine’s pressure, keeping it within an appropriate range to ensure that the backing paper remains undamaged during die cutting.

2. The die-cutting blade has become dull.

Currently, the service life of die-cutting blades on the market varies from tens of thousands to hundreds of thousands of cuts, depending on their material. It’s important to note that as the number of cuts increases, the blade gradually becomes dull—eventually reaching a point where it can no longer be used. During this process, the die-cutting performance also undergoes subtle changes. At first, when the blade is sharp, materials can be easily cut through with only minimal die‑cutting pressure. However, as usage accumulates and the blade grows increasingly dull, we are forced to increase the die‑cutting pressure in order to sever the material—and doing so often leads to damage to the liner. The most common sign of this is deep die‑cut marks on the liner’s surface. These marks are caused by the impact force exerted on the liner; although the liner may not appear to be completely cut through on the surface, the fibers within the liner have already been compromised, significantly reducing its tensile strength. As a result, such label products are highly prone to liner breakage during automated labeling processes. Therefore, we strongly advise all industry peers to pay close attention during production: the die‑cut marks on the liner must not be too deep, as excessive marks can weaken the liner’s structural integrity. If such issues arise, we recommend replacing the die‑cut blade with a new one.

3. Quality Issues with the Die-Cutting Base Plate

Most die-cutting machines use a die-cutting base plate beneath the material during operation to prevent direct contact between the cutting blade and the steel backing plate, thereby extending the lifespan of the blade. In general, die‑cutting base plates should be made from materials that strike a balance between softness and hardness—possessing a certain degree of elasticity while maintaining a smooth, flat surface (such as PVC plastic sheets). However, I’ve found that some materials used for die‑cutting base plates lack sufficient surface strength; after being struck by the cutting blade during the die‑cutting process, they deform very easily, leading to localized pressure fluctuations that can damage or even puncture the release liner. When faced with this kind of issue, operators often find it difficult to pinpoint the true cause, because the deformation of the base plate material is highly irregular. During production, operators may notice that adjusting local pressure immediately after detecting damage to the release liner seems to help—but not for long; before too much time passes, they’ll discover that damage to the release liner has reappeared in other areas. This cycle of constant troubleshooting without ever identifying the root cause continues until, after switching to a different die‑cutting base plate, the problem is finally resolved. Therefore, we’d like to remind everyone: if you encounter irregular, localized pressure variations, try replacing the die‑cutting base plate with one made from a different material and see whether the issue is resolved.

4. Material Quality Issues

There are many manufacturers in China producing self‑adhesive labels, and the quality of their products varies considerably. Self‑adhesive materials have extremely high requirements for product flatness; some small-scale manufacturers fail to maintain consistent adhesive thickness during the coating process, resulting in uneven thickness in certain areas of the product. Such self‑adhesive materials are prone to damaging the release liner during die-cutting. This type of failure also tends to occur irregularly, with the issue manifesting as occasional damage to the release liner even when die‑cutting pressure remains constant—sometimes the liner gets cut, while at other times the surface layer may not be fully penetrated. When encountering this problem, it is recommended to replace the self‑adhesive material.

5. Die-cutting Machine Issues

Unstable pressure in die-cutting machinery can also lead to damage to the backing paper, though this phenomenon is relatively rare—after all, the vast majority of die‑cutting machines on the market have been thoroughly tested. However, it’s still possible for some older equipment that has been in use for many years to suddenly develop issues. When the problem stems from the die‑cutting machine itself, it typically manifests as sudden, overall excessive or insufficient pressure during normal operation, often occurring without any discernible pattern. In such cases, you can contact the manufacturer of the die‑cutting machine for repairs.

2. Inaccurate die-cut spacing

Die-cut spacing refers to the distance between labels after die-cutting and waste removal. In most cases, depending on the customer’s specific application, the die-cut spacing for adhesive labels typically ranges from 2 to 3 mm. In daily production, it is common to encounter instances where the die-cut spacing is inaccurate—primarily manifesting as inconsistent spacing that alternates between too large and too small. Such label products also fail to meet quality standards. So, what causes this phenomenon?

1. The printing cursor spacing is inaccurate.

The spacing during die-cutting is determined by the die‑cut registration marks that are pre‑printed during the printing process. However, due to various issues, some printing equipment may introduce slight deviations in the spacing of the printed registration marks, resulting in inaccurate die‑cut spacing. This typically manifests as minor discrepancies between label spacings; sometimes the label spacing gradually increases or decreases in a periodic pattern, recurring at regular intervals—such as every few prints or roughly every ten prints. If you encounter this type of problem, die‑cutting alone cannot resolve it; instead, you’ll need to identify the root cause of the printing error and address it accordingly.

2. Die-cutting Machine Issues

As mentioned earlier, the die-cutting process typically requires tracking printing registration marks. If the photoelectric eye used on the die‑cutting machine to track these marks malfunctions, it can also lead to inaccurate die‑cut spacing. When this is the cause of inaccurate die‑cut spacing, the issue often manifests as consistently accurate spacing between printing registration marks, but with unstable die‑cut spacing—sometimes regular, sometimes irregular. Moreover, after running for a while, the photoelectric eye may no longer be able to detect the registration marks. In such cases, you can try re‑adjusting the photoelectric eye according to the operating procedures, or shutting down and restarting the machine before readjusting the photoelectric eye again. If the problem still persists, you’ll need to consider replacing the photoelectric eye on the die‑cutting machine. Of course, for manufacturers that operate two or more die‑cutting machines, you can also determine whether the issue lies with a specific die‑cutting unit by transferring the material to another machine for die cutting.

3. Material Deformation

Many thin-film adhesive materials tend to shrink and deform during the printing process due to the heat generated by UV lamps. These materials are also prone to misalignment issues during die-cutting. When encountering such problems, first measure whether the actual spacing of the print registration marks is smaller than the designed spacing. If you determine that this is the root cause of the spacing discrepancy, it must be addressed during the printing process. We can reduce the likelihood of material thermal deformation by lowering the UV lamp power or increasing the printing speed.

3. Die-Cutting “Flying Marks”

The so‑called “flying label” in die-cutting refers to the phenomenon where labels are lifted up along with the waste material during the die‑cutting process. The occurrence of “flying labels” is quite common in daily production; severe cases can lead to significant waste of raw materials and cause numerous problems for subsequent processing steps. The following are some of the main causes of die‑cutting “flying labels”:

1. The release force of the material is too low (due to excessively low temperature).

The bond between the adhesive layer and the release liner of a pressure-sensitive adhesive material is known as release force. If the release force of a pressure-sensitive adhesive material is too low, it can easily lead to “flying labels” during die-cutting. It’s important to note that the release force of many pressure-sensitive adhesive materials varies with temperature: generally speaking, as temperature rises, release force increases; conversely, when temperature drops, release force decreases. In winter, if the workshop temperature is too low, the release force of the pressure-sensitive adhesive material may also decrease, resulting in “flying labels” during die-cutting. As a general rule, it’s recommended that the production temperature in the workshop should not fall below 15°C. If “flying labels” still occur even at temperatures above this threshold, you should consider whether the issue lies with the quality of the pressure-sensitive adhesive material itself.

2. Excessive adhesive residue on the die-cutting blade

During the die-cutting process, residual adhesive gradually accumulates on the cutting blade. Once the accumulated adhesive reaches a certain level, it can lift the edges of the labels, effectively causing a pre‑peel on the die‑cut labels. As a result, during waste removal, the waste edge can easily pull up the labels, leading to “flying labels” during die cutting. Therefore, it’s important to promptly clean off residual adhesive from the cutting blade; alternatively, you can place sponge pads on the blade to prevent the blade from causing premature peeling of the labels. When necessary, you can also spray a silicone oil mist onto the blade to reduce the amount of residual adhesive on its surface.

3. The die-cutting blade is damaged or the edges are uneven.

If there are cracks in the blade of a die-cutting knife or if the joints are uneven, the label may not be fully cut through. During waste removal, the scrap edge can lift up the partially uncut labels, resulting in “flying labels” during die cutting. “Flying labels” caused by this issue are usually fairly predictable, and the edges of the labels will remain connected to the waste edge because they haven’t been completely severed. To resolve this problem, it’s recommended to replace the blade or thoroughly repair the die‑cutting plate.

4. The label area is too small.

The smaller the label area, the more likely it is to experience “flying label” issues. This is because the smaller the label area, the less force is required to peel the label away from the liner; consequently, even a slight external force can easily cause the label to detach from the liner, resulting in “flying labels.” For labels with an area smaller than 10×10 mm, it is generally recommended to use manual waste removal.

4. Waste Edge Breakage

1. The waste edge is too thin, and the material strength is insufficient.

Many label manufacturers, in their pursuit of economic benefits, design the waste edge of labels too narrowly during the production process, resulting in insufficient strength and eventual breakage of the waste edge. Generally speaking, the waste edge of paper-based adhesive materials should be at least 3 mm wide, while the waste edge of film-based adhesive materials should be at least 1 mm wide.

2. The release liner of the adhesive material has excessive peel strength.

Many adhesive materials fail to meet the required standards, exhibiting excessively high release liner adhesion. In some cases, it’s even extremely difficult to separate the face stock from the liner. When die-cutting and waste removal are performed, these materials are prone to tearing because the tensile force on the waste edge is weaker than the material’s release liner adhesion. Therefore, it’s best to check whether the release liner adhesion meets the specifications before starting adhesive processing and production.

3. Damage to the material edges

During transportation or processing, edge damage to adhesive materials is also a common cause of tear-off waste edge breakage. Therefore, during both transportation and processing, it’s crucial to avoid collisions or compression that could damage the edges of raw materials, so as not to create unnecessary trouble for subsequent die-cutting production.

4. The waste discharge roller is too thin.

For die-cutting equipment with excessively thin waste‑removal rollers, the waste edge is prone to breaking due to the excessive tensile force it experiences as it passes through the roller. To address waste‑edge breakage caused by this issue, we can either replace the waste‑removal roller or wrap a layer of sponge around the roller to increase its diameter.

5. Irregular tag shapes

Many labels are designed in non‑standard shapes, such as pentagrams or triangles. Due to their unique designs, these labels tend to concentrate stress along the waste‑removal edges, making them prone to breakage. In most cases, when dealing with non‑standard labels, it’s best to use manual waste removal or to forgo waste removal altogether.

5. Residual Adhesive Contamination of Labels During Die-Cutting

During the die-cutting process, residual adhesive often contaminates the label surface, leading to defective products. This issue is particularly common in the die-cutting of film-based adhesive labels, as the bond between the face stock and the adhesive in film-based adhesive materials is relatively weak, making it easier for the adhesive to bleed out during die-cutting. The following are some solutions to this problem:

1. Keep the die‑cutting blade clean.

The adhesive gradually accumulates on the die‑cutting blade during the die‑cutting process, then transfers from the blade to the surface of the pressure‑sensitive material. Therefore, keeping the die‑cutting blade clean is extremely important. In addition to regularly cleaning the die‑cutting blade during production, it’s best to spray a silicone oil mist onto the blade to reduce adhesive buildup.

2. The workshop temperature must not be too high.

If the temperature in the processing workshop is too high, it can increase the fluidity of the adhesive, making it more likely to seep out and contaminate the labels. Generally, the temperature in the adhesive label production workshop should be maintained between 20 and 25 degrees Celsius; this temperature range can significantly reduce adhesive leakage. We would also like to remind all industry peers that the recommended storage temperature for adhesive labels is also 20–25 degrees Celsius—exceeding this range can cause the adhesive to easily leak from the die-cut edges, affecting the end user’s normal operation.

3. Select appropriate materials.

There are many types of adhesives used in pressure-sensitive materials—also known as adhesives. Many pressure-sensitive label manufacturers typically opt for adhesives with relatively low fluidity when working with film substrates that are prone to adhesive bleed. This helps prevent adhesive leakage during the die-cutting process. Therefore, before producing pressure-sensitive labels, it’s advisable to communicate with material suppliers to select the most suitable substrate for your specific production needs, thereby minimizing label surface contamination caused by adhesive bleed.

6. Issues Related to Die-Cutting Blade Angle and Hardness

Finally, this article would like to remind everyone that the die-cutting blade angle and hardness vary depending on the specific adhesive material being used. Currently in China, die‑cutting blades are typically available in 42° and 52° angles. A 42° blade is primarily used for cutting film-based adhesive materials, while a 52° blade is mainly employed for cutting paper-based adhesive materials. Different manufacturers have varying standards for die‑cutting blade hardness: some use Shore hardness as the benchmark, while others follow their own proprietary criteria. Generally speaking, die‑cutting blades designed for film labels tend to be slightly harder but less wear‑resistant, whereas blades for paper labels are relatively softer yet more abrasion‑resistant. Each manufacturer offers products tailored to these two types of label materials; for specific applications, it’s best to consult with the manufacturer directly. For now, the key takeaway is simply to pay attention to these distinctions.

7. Die-Cutting Adhesive Overflow

Die-cut glue overflow refers to the phenomenon where adhesive oozes out from the edges of a label after it has been processed through die-cutting. It is a common defect in pressure-sensitive adhesive products. Glue overflow can lead to issues such as aesthetic defects in the label, print contamination, and poor peel performance. The problem of die-cut glue overflow can be addressed from the following aspects:

1. Analysis of Label Material Properties: Different material models feature varying types of adhesives and distinct processing characteristics. Therefore, before production begins, you should consult with the material supplier about the relevant performance attributes and select materials that are well suited to your specific processing techniques.

2. Label Processing and Storage Environment Control: The temperature of the label processing and storage environment should be maintained within a range of 23°C ± 3°C, and the humidity should be kept at approximately 55% ± 5%. Excessively high temperature and humidity can increase the fluidity of the adhesive. In actual production, we can clearly observe that die-cutting glue overflow is relatively common during summer production, whereas it rarely occurs in winter—this is precisely the underlying reason.

3. Quality Control for Die-Cutting Labels: It is essential to use sharp cutting tools for die-cutting labels. Blunt blade edges can cause the adhesive on the label to be squeezed and displaced, leading to adhesive overflow along the label edges during the die‑cutting process. Excessively deep die‑cutting pressure can also result in excessive compression of the label adhesive, while die‑cutting pressure that is too shallow may cause the adhesive to form filaments during die cutting, ultimately resulting in adhesive overflow at the label edges or on the label surface. Therefore, the selection of die‑cutting blades is crucial.

4. Control of Label Processing: During label processing, sliding friction on the labels should be avoided. Components that experience sliding friction with the labels are prone to accumulating die-cut adhesive, which can then contaminate the label edges. This type of adhesive overflow typically exhibits distinct patterns and directional tendencies in its placement on the label.

5. Label Rewinding Tension Control: Excessive rewinding tension can lead to excessive compression of the label adhesive, potentially causing the label to slip on the release liner and resulting in adhesive overflow. For non‑rectangular, irregularly shaped labels, uneven rewinding tension along the axial direction can easily cause localized over‑tension, leading to adhesive overflow in specific areas. Similarly, small, square labels are prone to adhesive overflow under the same pressure because they experience higher pressure per unit area.

8. Die-cutting must not be interrupted.

First, you need to check whether the locations where die-cutting fails are repetitive. If they occur in a regular, recurring pattern, then the problem is almost certainly related to the die‑cutting blade. In such cases, if you’re using round‑to‑round die cutting, you can increase the overall die‑cutting pressure; this may resolve the issue of incomplete die cutting while also accelerating wear on the die‑cutting blade. If, even within the allowable pressure range, the problem of incomplete die cutting still cannot be solved, then the only option is to replace the die‑cutting blade with a new one. For flat‑to‑flat die cutting, you can adjust the pressure locally.

If the issue of incomplete die cutting does not occur in a regular, repetitive pattern, the problem may be caused by inaccuracies in the machine’s gears, improper material running tension, or insufficient die‑cutting pressure. In such cases, it is necessary to check the material running tension and adjust the die‑cutting pressure to resolve the issue.